PKU Management, Quantitative by LCMSMS

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PKU MANAGEMENT, QUANTITATIVE BY LCMSMS

TURNAROUND TIME:   3 - 4 days
 
PERFORMED :  Wednesday
 
TESTING METHODOLOGY: High Performance Liquid Chromatography Triple Quadrupole Mass Spectrometer (LC/MSMS).
 
SPECIMEN REQUIREMENTS:
  • Collect: On special filter paper or in sodium heparin tube
  • Min. Collection: 1.0 mL whole blood
  • Transport: Air dry the filter paper card for 3 - 6 hours before transport.  If collected in sodium heparin tube, transport on ice immediately.
  • Stability: Filter paper stored refrigerated: 1 month; Sodium Heparin tube: 1 week
  • Unacceptable Conditions: Filter paper cards collected longer than 14 days prior.  Sodium heparin tubes stored or transported at room temperature.
REFERENCE INTERVAL:
Normal ranges are based upon literature values and expert opinion.
PKU Management
Differential
Acronym
Analyte Cutoff
(µmol/L)
Analyte Ratio Cutoff
  Phenylketonuria
  PKU
  Phe > 182
  Phe/ Tyr > 2.0
  Tyrosinemia
  NA
  Tyr > 400
  NA
 
INTERPRETATIVE DATA:
Clinical correlation is necessary for appropriate interpretation of results.  Additional required information includes age, gender, diet (e.g., TPN therapy), drug therapy, and family history. Clinical information should be included on the Biochemical Genetics Test Requisition Form.
Analytic Sensitivity: >99%
Test Limitations: Filter paper card collection may yield erroneous results due to improper filling of specimen testing area. Please consult Simple Spot Check Guide for appropriate application.
Specimens that are not allowed to air dry horizontally at room temperature for 3 - 6 hours, before transporting, may adversely affect the test results.
 
INDICATIONS FOR USE: Intended for the monitoring of phenylketonuria or tyrosinemia in patients on a metabolic diet.
 
ADDITIONAL RESOURCES:
The American College of Medical Genetics Action Sheets and Algorithms for Newborn Screening: www.acmg.net/resources/policies/ACT/condition-analyte-links.htm
Genetics Home Reference:   http://www.ghr.nlm.nih.gov/gene/PAH
Metabolic and Information Center: www.metagene.de